In order to make X-ray fluorescence, XRF, measurements, samples need to be prepared. The sample may be powdered and placed in a platinum or gold crucible with flux. The crucible is heated to a temperature at which the flux is liquid and the sample dissolves in the flux. The melt is then cooled leaving a glassy ‘bead’ on the inside of the crucible or casting dish with the elements of the sample dispersed inside the deposit as a solid solution. XRF measurements may then be made on the deposit or bead.
A problem can however occur with some materials which are highly reactive. In particular, where the sample is highly reactive the sample can undergo a highly exothermic reaction process with oxygen leading to damage to the platinum crucible.
To address this issue, a procedure was proposed by Rutherford. A flux material is placed in a platinum crucible without the sample and heated in a furnace to above the temperature at which the flux melts. The crucible is then removed from the furnace and rotated around to be cooled by ambient air for sufficient time for a glassy flux surface to form in the crucible. The sample is then added to the crucible inside the glassy flux surface and heated in the furnace.
This procedure however is both difficult and dangerous since the very hot crucible at a temperature above 1000° C. is typically rotated outside the furnace by hand. This method accordingly is rarely used except by the most experienced scientists.
There accordingly remains a need for a safer and easier way of preparing XRF samples for analysis of reactive materials.
CN102331364A teaches a melted sampling method for preparing aluminium magnesium calcium iron alloy samples. A lithium tetraborate wall of a platinum crucible is first prepared. AU 2010 249 195 teaches a composition of X-ray flux including lithium borate.